Question

The element with atomic number 51 belongs to the _____ period of the periodic table.

Answer 1

• Every element is arranged in the periodic table based on its atomic number.
• Each horizontal row is considered as a period and the vertical column as a group. Each group and the period are specified by numbers.
• The electronic configuration of the element is$\left[\mathrm{Kr}\right]4{\mathrm{d}}^{10}5{\mathrm{s}}^{2}5{\mathrm{p}}^3$. It has $5$ valence electrons.
• The period number of an element is equal to the number of valence electrons.
• Thus, the element with an atomic number $51$ belongs to group $5$.

Hence, The element with an atomic number $51$ belongs to ${\mathbf{5}}^{\mathbf{th}}$ period of the periodic table.